It is often required to talk to someone in an organization without knowing his real name. We only want to talk to someone in charge of a service for example.
The Internet has defined may pseudo-users. Here is a list of the one you should define on your system (on the mail-host server)
Linux system have several administrative accounts which received mail. It is a pain to manually log as one of those user just to check if there is any mail. This is a good idea to redirect those account to a real user (you ?).
Here is a list of those accounts
On small site, there is a single administrator for the complete network. Instead of setting all those aliases pointing to him, you may save some time and point all to the pseudo-user admin which is itself and alias pointing to the administrator.
This may save time.